TVariant | Unreal Engine 5.7 Documentation

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A type-safe union based loosely on std::variant. This flavor of variant requires that all the types in the declaring template parameter pack be unique. Attempting to use the value of a Get() when the underlying type is different leads to undefined behavior.


Name	TVariant
Type	class
Header File	/Engine/Source/Runtime/Core/Public/Misc/TVariant.h
Include Path	#include "Misc/TVariant.h"

Syntax

template<typename T, typename... Ts>  
class TVariant : private std::conditional_t<!std::is_trivially_destructible_v< T >||(!std::is_trivially_destructible_v< Ts >||...), UE::Core::Private::TDestructibleVariantStorage< T, Ts... >, UE::Core::Private::TVariantStorage< T, Ts... > >

Inheritance Hierarchy

std::conditional_t||(!std::is_trivially_destructible_v< Ts >||...), UE::Core::Private::TDestructibleVariantStorage< T, Ts... >, UE::Core::Private::TVariantStorage< T, Ts... > > → TVariant

Constructors

Name	Remarks	Include Path
TVariant ( UE::Core::Private::TUninitializedType< U >&& )	INTERNAL USE ONLY Do not call this constructor, it will put the variant in a bad state.	Misc/TVariant.h
TVariant ()	Test for 255 here, because the parameter pack doesn't include the initial T.	Misc/TVariant.h
TVariant ( const TVariant& Other )	Copy construct the variant from another variant of the same type	Misc/TVariant.h
TVariant ( TVariant&& Other )	Move construct the variant from another variant of the same type	Misc/TVariant.h
TVariant ( TInPlaceType< U >&&, ArgTypes&&... Args )	Perform in-place construction of a type into the variant	Misc/TVariant.h

Destructors

Name	Remarks	Include Path	Unreal Specifiers
~TVariant()	Defer to the storage as to how to destruct the elements.	Misc/TVariant.h

Typedefs

Name	Type	Remarks	Include Path
Super	std::conditional_t		(!std::is_trivially_destructible_v< Ts >		...), UE::Core::Private::TDestructibleVariantStorage< T, Ts... >, UE::Core::Private::TVariantStorage< T, Ts... > >		Misc/TVariant.h

Functions

Public

Name	Remarks	Include Path
void Emplace ( ArgTypes&&... Args )	Set a specifically-typed value into the variant using in-place construction	Misc/TVariant.h
U & Get ()	Get a reference to the held value.	Misc/TVariant.h
const U & Get ()	Get a reference to the held value.	Misc/TVariant.h
const U & Get ( const TIdentity_T< U >& DefaultValue ) const	Get a reference to the held value if set, otherwise the DefaultValue	Misc/TVariant.h
SIZE_T GetIndex()	Returns the currently held type's index into the template parameter pack	Misc/TVariant.h
bool IsType()	Determine if the variant holds the specific type	Misc/TVariant.h
void Set ( typename TIdentity< U >::Type&& Value )	Set a specifically-typed value into the variant	Misc/TVariant.h
void Set ( const typename TIdentity< U >::Type& Value )	Set a specifically-typed value into the variant	Misc/TVariant.h
U * TryGet ()	Get a pointer to the held value if the held type is the same as the one specified	Misc/TVariant.h
const U * TryGet ()	Get a pointer to the held value if the held type is the same as the one specified	Misc/TVariant.h

Static

Name	Remarks	Include Path	Unreal Specifiers
static SIZE_T IndexOfType()	Lookup the index of a type in the template parameter pack at compile time.	Misc/TVariant.h

Operators

Name	Remarks	Include Path	Unreal Specifiers
TVariant & operator= ( TVariant&& Other )	Move assign a variant from another variant of the same type	Misc/TVariant.h
TVariant & operator= ( const TVariant& Other )	Copy assign a variant from another variant of the same type	Misc/TVariant.h

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